It would have been impossible to imagine a year ago that the Republican Party’s leaders would be effectively serving as enablers of Russian interference in this country’s political system. Yet, astonishingly, that is the role the Republican Party is playing.

U.S. intelligence services have stated that the Russian government interfered in the 2016 presidential election with the intention of swinging it to one side. Knowing how cautious the intelligence community is in making such judgments, and given the significance of this particular finding, the evidence must be compelling. At the very least, any reasonable person would have to conclude that there is enough evidence to warrant a serious, wide-ranging and open investigation. Polls suggest that a majority of Americans would like to see such an investigation carried out.

It’s important at this time of intense political conflict to remain focused on the most critical issue. Whether certain individuals met with Russian officials, and whether those meetings were significant, is secondary and can eventually be sorted out. The most important question concerns Russia’s ability to manipulate U.S. elections. That is not a political issue. It is a national security issue. If the Russian government did interfere in the United States’ electoral processes last year, then it has the capacity to do so in every election going forward. This is a powerful and dangerous weapon, more than warships or tanks or bombers. Neither Russia nor any potential adversary has the power to damage the U.S. political system with weapons of war. But by creating doubts about the validity, integrity and reliability of U.S. elections, it can shake that system to its foundations.

The United States has not been the only victim. The argument by at least one former Obama administration official and others that last year’s interference was understandable payback for past American policies is undermined by the fact that Russia is also interfering in the coming elections in France and Germany, and it has already interfered in Italy’s recent referendum and in numerous other elections across Europe. Russia is deploying this weapon against as many democracies as it can to sap public confidence in democratic institutions.

The democracies are going to have to figure out how to respond. With U.S. congressional elections just 20 months away, it is essential to get a full picture of what the Russians did do and can do here, and soon. The longer the American people remain in the dark about Russian manipulations, the longer they will remain vulnerable to them. The longer Congress fails to inform itself, the longer it will be before it can take steps to meet the threat. Unfortunately, the present administration cannot be counted on to do so on its own.

There’s no need to ask what Republicans would be doing if the shoe were on the other foot — if the Russians had intervened to help elect the Democratic nominee. They would be demanding a bipartisan select committee of Congress, or a congressionally mandated blue-ribbon panel of experts and senior statesmen with full subpoena powers to look into the matter. They would be insisting that, for reasons of national security alone, it was essential to determine what happened: what the Russians did, how they did it and how they could be prevented from doing it again. If that investigation found that certain American individuals had somehow participated in or facilitated the Russian operation, they would insist that such information be made public and that appropriate legal proceedings begin. And if the Democrats tried to slow-roll the investigations, to block the creation of select committees or outside panels, or to insist that investigations be confined to the intelligence committees whose inquiries and findings could be kept from the public, Republicans would accuse them of a coverup and of exposing the nation to further attacks. And they would be right.

But it is the Republicans who are covering up. The party’s current leader, the president, questions the intelligence community’s findings, motives and integrity. Republican leaders in Congress have opposed the creation of any special investigating committee, either inside or outside Congress. They have insisted that inquiries be conducted by the two intelligence committees. Yet the Republican chairman of the committee in the House has indicated that he sees no great urgency to the investigation and has even questioned the seriousness and validity of the accusations. The Republican chairman of the committee in the Senate has approached the task grudgingly. The result is that the investigations seem destined to move slowly, produce little information and provide even less to the public. It is hard not to conclude that this is precisely the intent of the Republican Party’s leadership, both in the White House and Congress.

This approach not only is damaging to U.S. national security but also puts the Republican Party in an untenable position. When Republicans stand in the way of thorough, open and immediate investigations, they become Russia’s accomplices after the fact. This is undoubtedly not their intent. No one in the party wants to help Russia harm the United States and its democratic institutions. But Republicans need to face the fact that by slowing down, limiting or otherwise hampering the fullest possible investigation into what happened, that is what they are doing.

It’s time for the party to put national security above partisan interest. Republican leaders need to name a bipartisan select committee or create an outside panel, and they need to do so immediately. They must give that committee the mission and all the necessary means for getting to the bottom of what happened last year. And then they must begin to find ways to defend the nation against this new weapon that threatens to weaken American democracy. The stakes are far too high for politics as usual.